1. Field of the Invention
The present invention relates to an electronic apparatus, and in particular, to an electronic apparatus in which a plurality of differential transmission lines is mounted on one wiring board.
2. Description of the Related Art
The frequency of digital signals used in electronic apparatuses, such as a digital camera, is increasing year by year. Further, the signal transmission rate is also increasing. To enable signal transmission at a high rate, recently differential transmission, represented by low voltage differential signaling (LVDS) may be used. LVDS is an input/output signal level specification for the purpose of realizing high-speed transmission of several hundred M bit/second or higher with an amplitude reduced to several hundred mV, which is less susceptible to the effects of noise produced by performing differential transmission over impedance-controlled wiring.
Further, in electronic apparatuses such as a digital camera, an interface such as a universal serial bus (USB) or a high-definition multimedia interface (HDMI) employing differential transmission may be used to communicate with an external device. In this case, to increase the degree of freedom for mounting of a USB connector or a HDMI connector in the electronic apparatus, the interface may be mounted on a printed wiring board different to the printed wiring board that a system integrated chip (IC) is mounted on. Japanese Patent Application Laid-Open No. 2007-166290 discusses connecting a USB or HDMI signal with a printed wiring board on which the system IC is mounted via a connector for signal connection.
When a plurality of interfaces, like USB and HDMI, employing differential transmission is mounted on one printed wiring board, differential transmission lines controlled with respectively different impedances are mounted on one printed wiring board. In this case, crosstalk between the differential transmission lines has to be prevented.